This invention relates to an injection molding device and more particularly to a parison molding device disposed on an injection stretching blow molding machine.
In the parison molding device, a parison molding mold along with a mold clamping device is disposed at a right angle to a transfer board which is rotated intermittently about a support shaft. An injection device is located at one side of the parison molding mold, and accordingly, nozzle touching is achieved at a right angle to the mold clamping direction. Such an arrangement poses a drawback that the mold laterally oscillates merely by application of the nozzle touching force to the side since the mold is urged from opposite ends thereof by the mold clamping device and since there is nothing provided at the opposite side of the mold to receive the nozzle touching force.
While the oscillation of the mold is in the range of a very minor dimension, it results in an uneven wall thickness distribution in the molded articles, particularly in cylindrical and elongated molded articles such as parisons. Consequently, it is difficult to form a parison which will, when subsequently blow molded into a hollow molded article, have an even distribution of wall thickness, as is desired.
The present invention has been achieved in order to eliminate those drawbacks noted above and provides an arrangement wherein the side of the mold opposite the nozzle touch is urged by a force equal to the nozzle touching force only when nozzle touching takes place, thereby preventing displacement and oscillation of the mold due to the nozzle touching force and preventing occurrence of uneven wall thickness of a molded article while allowing free opening and closing of the mold.
The present invention will be further described by way of a vertical injection molding machine shown in the drawings.